Temporal Branch of the Facial Nerve: The Danger Zone
- Nerve
Quick facts
- Origin
- Branch of the facial nerve that leaves the upper border of the parotid gland.
- Course
- Crosses the zygomatic arch and rises through the temple in the temporoparietal fascia layer, toward the eyebrow.
- Surface landmark
- Pitanguy line: from 0.5 cm below the tragus to 1.5 cm above the tail of the eyebrow.
- Muscles
- Frontalis, upper part of the orbicularis oculi and part of the corrugator.
- Relevance in orofacial harmonization (HOF)
- Defines the temple danger zone; injury leaves the eyebrow drooping and the forehead without movement on the affected side.
The temporal branch of the facial nerve, also called the frontal branch, leaves the upper border of the parotid, crosses the zygomatic arch and rises through the temple to the frontalis muscle, the upper part of the orbicularis oculi and part of the corrugator. Because it travels in a relatively superficial layer with little protection, the temple is described as a danger zone for this nerve. Injury leaves the eyebrow drooping and the forehead without movement on the affected side.
What is the course of the temporal branch?
| Segment | What to look for |
|---|---|
| Exit | Upper border of the parotid gland, in front of the ear |
| Zygomatic arch | Crosses the arch usually at its middle third, in a plane superficial to the periosteum |
| Temple | Rises within or just below the temporoparietal fascia, the superficial layer of the temporal fasciae |
| Arrival | Enters the frontalis through its deep surface, above and lateral to the eyebrow |
The classic surface landmark is the Pitanguy line, drawn from a point 0.5 cm below the tragus to a point 1.5 cm above the tail of the eyebrow. It shows the approximate course, not the exact one: the nerve usually divides into several fine branches, with variation between people and between sides.
Why is the temple called a danger zone?
- Superficial layer: over the zygomatic arch the nerve has little protection, between the skin and the bone.
- Vessels in the same territory: the frontal branch of the superficial temporal artery runs in the same layer, and the sentinel vein marks the region lateral to the eyebrow.
- Little room for error: the temporal fat pad and the fasciae form thin layers, and the anatomy changes with age and weight loss.
How does it show up in the assessment?
- Functional test: ask the person to raise the eyebrows and frown. Prior asymmetry must be recorded before any procedure.
- Telling it apart from toxin: a drooping eyebrow after toxin in the frontalis or glabella is a temporary effect of the product, not nerve injury. See ptosis after botulinum toxin.
- Surgical history: facelift, zygomatic arch fracture surgery and previous procedures in the temple change the local anatomy.
Also called: frontal branch of the facial nerve, frontotemporal branch, ramus temporalis nervi facialis.
Frequently asked questions
What happens if the temporal branch of the facial nerve is injured?
The person cannot raise the eyebrow on the affected side, the forehead stays smooth on that side and the eyebrow tends to drop. Because the nerve is motor, there is no numbness. The course depends on the type of injury.
Are the temporal branch and the frontal branch the same thing?
Yes, in clinical practice both names refer to the branch of the facial nerve that goes to the frontalis muscle. Some authors describe the frontal branch as the final part of the temporal branch.